Ionic liquids are liquids composed of ions that are fluid around or below 100 degrees C. (Science (2003) 302:792–793). Ionic liquids exhibit negligible vapor pressure, and with increasing regulatory pressure to limit the use of traditional industrial solvents due to environmental considerations such as volatile emissions and aquifer and drinking water contamination, much research has been devoted to designing ionic liquids that could function as replacements for conventional solvents.
Ionic liquids generally consist of salts of organic cations, such as the N-alkylpyridinium, 1,3-dialkylimidazolium, tetraalkylammonium, tetraalkylphosphonium and trialkylsulfonium cations. Demberelnyamba, Shin and Lee (Chem. Commun. (2002) 1538–1539) describe petroleum-derived ionic liquids based on N-vinyl-γ-butyrolactam having the Formula:
wherein X− is a bromide or tetrafluoroborate anion.
Described herein are novel compositions based on pyrrolidinones that are useful as ionic liquids. The compositions of the present invention exhibit unique properties due to separation of the ammonium cation from the pyrrolidinone ring using a variable-length alkyl spacer group.